System and Method for Providing IpV6 Services

ABSTRACT

A system for providing IPv6 services, including a node registration agent for use in applying for a home address for the device, registering the device to a home agent and informing the device of the home address. A method for providing IPv6 services, comprising: the device accessing an IPv6 network and acquiring a forwarding address; the device making a remote registration to the node registration agent; the node registration agent applying for a home address for the device, registering the device to the home agent, and informing the device of the home address; the communication counterpart of the device sending messages using the home address as the destination address; the home agent receiving the message and forwarding the message to the forwarding address of the device; and eventually providing the device with the IPv6 services. Application of the system and method reduces the cost, and makes possible the IPv6 services.

FIELD OF THE INVENTION

The invention relates to Internet Protocol (IP) technologies, and moreparticularly, to a system and a method for providing Internet Protocolversion 6 (IPv6) services.

BACKGROUND OF THE INVENTION

The present Internet Protocol version 4 (IPv4) has many disadvantages insuch aspects as address capacity, peer-to-peer IP connection, quality ofservice, network security, and mobility. The huge address capacity aswell as various potential advantages and functions provided by IPv6makes it an important foundation for the next generation network.Compared with IPv4, an important advantage of IPv6 is the real mobility.Mobile Internet Protocol version 6 (Mobile IPv6) could provide moreflexibility for new functions and services. Through simple extensions,Mobile IPv6 could satisfy the demands of a large number of mobiledevices, and provide a globally unique IP address for each mobileterminal operating in the Internet. Thus, the global problem of mobilityrelated to the network and the accessing technology could be solved.

Although IPv6 network has more advantages than IPv4, they will coexistfor a long time. At present, almost every network and access devicesupports IPv4, thus it is impractical to switch from IPv4 to IPv6quickly. In many cases of such coexistence, the devices in an IPv4network would have the need for IPv6 services, so do the devices in anIPv6 network different from that of their communication counterparts,thus leading to the issue of how to provide IPv6 services for suchdevices.

In order to provide devices with IPv6 services when an IPv4 network andan IPv6 network coexist, one present solution is upgrading the presentnetwork to a network supporting the IPv4 & IPv6 dual protocol stacks.According to this solution, all the 3^(rd) layer network devices such asrouters and switches, as well as user terminals in the network areupgraded to support IPv6 & IPv4 dual protocol stacks. Each device has anIPv4 address and an IPv6 address. Therefore, devices could communicatewith the IPv4 protocol stack when allowed; and the devices could alsouse the IPv6 protocol stack to communicate when the IPv4 protocol stackcould not guarantee a normal communication due to the private addressproblem as a result of the NAT devices existing in the network. Themethod of upgrading the present network to the network supporting theIPv4 & IPv6 dual protocol stacks requires a complete upgrading of allthe 3^(rd) layer network devices such as routers and the 3^(rd) layerswitches, which leads to further investment in the network devices andcosts so much that the method is difficult to extend. Meanwhile, when adevice roams to another network, especially to the network onlysupporting IPv4, the IP address of the device using such a method has tobe changed as well, and the IP address could not be used as a uniqueidentifier of the device.

In the prior art, devices could also access the IPv6 network for somecertain services in a standard tunnel mode, wherein the tunnel mayinclude an Intra-site Automatic Tunnel Addressing Protocol (ISATAP)tunnel, a 6 to 4 tunnel, a configured tunnel, a Tunneling IPv6 over UDPthrough NATs (TEREDO) tunnel. When the device accesses the IPv6 networkthrough a standard tunnel, an IPv6 address associated to the tunnelcould be acquired from a tunnel gateway through which the device couldmake communications to receive IPv6 services. Being related to thenetwork configuration, the IPv6 service provided through a standardtunnel mechanism is not complete, e.g. the roaming service from an IPv6network to an IPv4 network is not supported. Moreover, the IPv6 addressgenerated through the standard tunnel mechanism is usually related tothe IPv4 address of the device, and the IPv4 address is usually adynamic address. When the IPv4 address of a device changes, the IPv6address thereof has to change correspondingly, making it impossible toidentify a device by the IP address, reducing the effectiveness of thepeer-to-peer communications between devices. Because the IPv6 addressacquired by the device is related to the IPv4 address, the routingability of the IPv6 address in the Internet is weak, e.g. a 6 to 4address is usually used only in local communications, which confinesnormal communication services for the device as well.

SUMMARY OF THE INVENTION

The present invention proposes a system for providing IPv6 services toreduce the investment cost.

The invention also proposes a method for providing IPv6 services tosolve the problem of limited effectiveness of the peer-to-peercommunications when the IPv6 network is accessed in a tunnel mode.

The technical solution of the invention involves: a method for providingInternet Protocol version 6 (IPv6) services, includes:

setting a node registration agent in advance in an IPv6 network;

a device accessing the IPv6 network and acquiring a forwarding address;

registering the device to the node registration agent which applies fora home address for the device, registers the home address to a homeagent and informs the device of the home address;

a communication counterpart of the device sending a message using thehome address as the destination address;

the home agent, after receiving the message, forwarding the message tothe forwarding address of the device;

providing the device with IPv6 services.

The step of the device accessing the IPv6 network includes:

the device accessing the IPv6 network from an Internet Protocol version4 (IPv4) network through a tunnel gateway;

the method, between the step of the device accessing the IPv6 networkand acquiring the forwarding address and the step of registering thedevice to the node registration agent which applies for a home addressfor the device, registers the home address to a home agent and informsthe device of the home address, further includes:

registering the device to the tunnel gateway which applies for aroutable IPv6 address for the device and sets up a mapping relation fromthe forwarding address to the routable IPv6 address;

the step of registering the device to the node registration agentincludes:

the tunnel gateway registering the device to the node registrationagent;

the step of the node registration agent informing the device of the homeaddress includes:

the node registration agent informing the tunnel gateway of the homeaddress, and the tunnel gateway informing the device of the homeaddress;

the step of forwarding the message to the forwarding address of thedevice includes:

the home agent forwarding the message to the routable IPv6 address, thetunnel gateway forwarding the message to the forwarding address; and

the method, between the step of the home agent forwarding the message tothe forwarding address of the device and the step of providing thedevice with IPv6 services, further includes:

the device instructing the communication counterpart through a bindingupdate process to communicate with the device using the routable IPv6address.

The step of the device accessing the IPv6 network includes:

the device directly accessing the local IPv6 network from an IPv6network other than the local IPv6 network; and

the step of providing the device with the IPv6 services includes:

forwarding the message using the mobile IPv6 forwarding mechanism toprovide the IPv6 services for the device.

The step of providing the device with the IPv6 services includes:

providing the device roaming to an IPv4 network with the IPv6 services,including:

the device accessing the IPv6 network through a tunnel and acquiring anIPv6 address 1;

registering the device to the tunnel gateway;

the tunnel gateway applying for a routable IPv6 address 2 for the deviceand setting up a mapping relation from the IPv6 address 1 to theroutable IPv6 address 2;

the tunnel gateway registering the routable IPv6 address 2 to the homeagent for the device and informing the home agent that the routable IPv6address is the forwarding address of the device;

the device acquiring the IPv6 address 2 from the tunnel gateway;

the communication counterpart of the device sending a message throughthe home address of the device;

the home agent receiving the message and forwarding the message to theIPv6 address 2;

the tunnel gateway receiving the message and forwarding the message tothe IPv6 address 1;

the device receiving the message and starting a binding update process;the communication counterpart communicating with the device through theIPv6 address 2, the device receiving the IPv6 services.

A system for providing Internet Protocol version 6 (IPv6) services,includes:

an IPv6 network;

a home agent in the IPv6 network; and

a node registration agent used in the IPv6 network to apply for a homeaddress for a device from the home agent, register for the device to thehome agent, and inform the device of the home address.

The system further including:

an IPv4 network and a tunnel gateway; wherein

the tunnel gateway locates between the IPv4 network and the IPv6network, supporting a remote registration from the tunnel gateway to thenode registration agent and forwarding device messages.

The node registration agent is integrated on the home agent or is aseparate device.

The tunnel gateway is a separate device or a device in the sub-networkwhere the tunnel access device locates. As shown in the above solution,the invention proposes a system for providing the IPv6 service. Thesystem includes an IPv6 network and a node registration agent in theIPv6 network which applies for a home address for the device, registersthe home address to a home agent for the device, and informs the deviceof the home address having been applied for. By adding the noderegistration agent in the IPv6 network, when a device accesses the localIPv6 network from another IPv6 network, the node registration agentcould acquire the home address for the device through a remoteregistration; then the device binds the home address with the forwardingaddress acquired while accessing the IPv6 network; the communicationcounterpart of the device sends a message using the home address of thedevice as the destination address; the home agent receives the messageand forwards the message to the forwarding address acquired by thedevice while accessing the IPv6 network; and eventually the IPv6 serviceis implemented. As a result, according to the invention, it is notnecessary to upgrade the layer 3 network devices like routers to providecomprehensive IPv6 services for the devices accessing the local IPv6network from other IPv6 networks, which lead to a great reduction in theinvestment cost.

Meanwhile, when a device accesses an IPv6 network from an IPv4 networkthrough a tunnel, the system in accordance with this invention providesvia the tunnel gateway thereof a function that supports not only remoteregistration from the tunnel gateway to the node registration agent butalso forwarding of device messages. The device could acquire the homeaddress through the remote registration from the tunnel gateway to thenode registration agent, and receive the IPv6 services through themessage forwarding by the tunnel gateway. Then the device could beprovided with the IPv6 service when the device accesses the IPv6 networkthrough a tunnel.

The invention also proposes a method for providing IPv6 services. Whileaccessing a IPv6 network, a mobile node is registered to the home agentthrough the remote registration mechanism, taking the IPv6 addressacquired through the remote registration process as its home address,and the IPv6 address acquired when accessing the IPv6 network as itsforwarding address. Through the remote registration mechanism, themobile node is registered to the home agent and acquires a fixed globalIPv6 address for the convenience of communications between IPv6 devices,which has solved the problem of limited effectiveness of thepeer-to-peer communications when the IPv6 network is accessed in thetunnel mode. Meanwhile, according to the method, the mobile devicescould roam between IPv4 and IPv6 networks with the support of the homeagent, making it possible to provide more IPv6 services withoutincreasing the investment cost.

In addition, because the mobile node has been registered on the homeagent in accordance with the invention, the device has acquired a fixedglobal IPv6 address which would not change as the mobile node roams toother networks. Thus IP addresses could be taken as the real identifierfor the devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a system for providing IPv6services in accordance with an embodiment of the invention;

FIG. 2 is a schematic diagram illustrating a system that provides IPv6services for devices accessing through a tunnel in accordance with anembodiment of the invention;

FIG. 3 is the overall flowchart of providing IPv6 services in accordancewith the invention;

FIG. 4 is the flowchart of providing IPv6 services in accordance with anembodiment of the invention;

FIG. 5 is a schematic diagram illustrating the IPv6 services providedfor a device accessing an IPv6 network through a tunnel in accordancewith an embodiment of the invention;

FIG. 6 is the flowchart of providing a device roaming to a IPv4 networkwith IPv6 services in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

To make the purpose, solution and advantages of the invention clearer,the invention will be described in more detail hereinafter withreference to the drawings.

The key idea of the invention is to add a node registration agent in anIPv6 network. The node registration agent could apply for a home addressfor a device, registers the home address to a home agent for the deviceand informs the device of the home address applied for. When the deviceaccesses the local IPv6 network from another IPv6 network, the homeaddress could be acquired for the device through a remote registrationby the node registration agent; then the device binds the home addresswith the forwarding address acquired while accessing the IPv6 network,and communicates through the mobile IPv6 forwarding mechanism to obtainthe IPv6 service. When a device accesses the IPv6 network from an IPv4network through a tunnel, a tunnel gateway is further added to thesystem. The tunnel gateway supports not only the remote registrationfrom the tunnel gateway to the node registration agent, but also devicemessage forwarding, thus the device could acquire the home addressthrough the remote registration, and receive the IPv6 service throughthe message forwarding via the tunnel gateway.

FIG. 1 is a schematic diagram illustrating a system for providing IPv6services in accordance with an embodiment of the invention. As is shownin FIG. 1, the system includes an IPv6 sub-network A, an IPv6sub-network B and a node registration agent in the IPv6 sub-network A.The node registration agent applies for a home address for the device,registers the home address to the home agent for the device and informsthe device of the home address applied for. When the device accesses theIPv6 sub-network A from the IPv6 sub-network B, the device firstacquires a forwarding address, and makes a remote registration to thenode registration agent; the node registration agent applies for a homeaddress for the device, registers the home address to the home agent forthe device, and informs the device of the home address; the device thenacquires the home address from the node registration agent and binds thehome address with the forwarding address; eventually the device iscommunicated with through the mobile IPv6 forwarding mechanism so as tobe provided with the IPv6 service.

Based upon FIG. 1, FIG. 2 is a schematic diagram illustrating a systemfor providing the device accessing through a tunnel with the IPv6service in accordance with an embodiment of the invention. As shown inFIG. 2, the system includes the IPv6 sub-network, the node registrationagent in the IPv6 sub-network, an IPv4 network and a tunnel gatewaybetween the IPv4 network and the IPv6 network. The node registrationagent applies for the home address for the device, registers the homeaddress to the home agent for the device and informs the device of thehome address applied for. The tunnel gateway supports not only theremote registration from the tunnel gateway to the node registrationagent, but also device message forwarding. While accessing the IPv6network through the tunnel, the device acquires the IPv6 address, whichcould be assumed to be an IPv6 address A; the device registers to thetunnel gateway; the tunnel applies for, for the device, an IPv6 addressB which is routable in both the IPv6 network which the device accessesand the IPv6 network where the communication counterpart of the devicelocates, and sets up a mapping relation from the IPv6 address A to theroutable IPv6 address B; the tunnel gateway registers the device to thehome agent, acquires the home address of the device from the noderegistration agent; after the device acquires the home address, the homeaddress of the device is determined; and the IPv6 address A is taken asthe forwarding address 1 of the device while the IPv6 address B is takenas the forwarding address 2 of the device; and all the messages sent tothe device through these addresses could be used in a session in amobile IPv6 terminal, thus providing the devices with the IPv6 service.

In specific implementation, the node registration agent shown in FIG. 1and FIG. 2 could be a supplementary function on the home agent device,or be integrated in the other networks, or be a separate network device.The tunnel gateway shown in FIG. 2 could be a separate device, or beanother device in the sub-network where the tunnel access devicelocates.

FIG. 3 is a flow chart illustrating the process of providing IPv6services in accordance with the invention. The process includes:

Step 301: The device accessing an IPv6 network, acquiring a forwardingaddress.

Step 302: Registering the device to a node registration agent; the noderegistration agent applying for the home address, registering the homeaddress to the home agent for the device, and informing the device ofthe home address;

Step 303: A communication counterpart of the device sending a messagetaking the home address of the device as the destination address;

Step 304: The home agent receiving and forwarding the message to theforwarding address of the device;

Step 305: The device setting up a communication connection afterreceiving the message, which makes it possible to provide the devicewith the IPv6 service.

In the above process, in Step 301, the device could access the IPv6network from an IPv4 network through a tunnel or directly access theIPv6 network from another IPv6 network. If the device accesses the IPv6network through a tunnel, the tunnel gateway and the mobile IPv6forwarding mechanism will be used in Step 305 for providing the IPv6service; if the device accesses the IPv6 network directly from anotherIPv6 network, the mobile IPv6 forwarding mechanism will be used in Step305 for providing the IPv6 service.

Based upon the overall flow chart for providing IPv6 servicesillustrated in FIG. 3, FIG. 4 is a flow chart illustrating the processof providing the IPv6 service in accordance with an embodiment of theinvention, which includes:

Step 401: The device accessing an IPv6 network, acquiring an IPv6address A.

The device will acquire an IPv6 address when accessing the IPv6 network,which could be assumed to be IPv6 address A.

Step 402: Determining whether the device accesses the IPv6 networkthrough a tunnel, if the device accesses the IPv6 network through atunnel, proceeding to Step 409 and the subsequent steps, otherwiseproceeding to Step 403 and the subsequent steps.

Step 403: Determining whether the device is in the same sub-network asthe home agent, if the device is in the same sub-network as the homeagent, proceeding to Step 404, otherwise proceeding to Step 405 and thesubsequent steps.

Step 404: Conducting communications through the mobile IPv6 registrationand forwarding mechanism, providing the device with the IPv6 service,and then terminating the process.

Here, when the device accesses the IPv6 sub-network from another IPv6sub-network directly, if the device is in the same IPv6 sub-network asthe home agent, the communications for providing the IPv6 service couldbe conducted through the mobile IPv6 registration and forwardingmechanism instead of the remote registration mechanism.

Step 405: Registering the device remotely to the home agent through thenode registration agent.

Step 406: The device acquiring the IPv6 home address from the noderegistration agent.

Step 407: The device binding the home address with the forwardingaddress for data packet transmission, i.e. for receiving and sending themessages.

Step 408: Conducting communications using the mobile IPv6 forwardingmechanism to provide the IPv6 service for the device.

Steps 405 to 408 are the registration process of a device that accessesthe local IPv6 sub-network from another IPv6 sub-network but is not inthe same sub-network as the home agent. The device could receive theIPv6 service by communicating with the mobile IPv6 forwarding mechanismin Step 408.

Step 409: The device registers to the tunnel gateway.

Step 410: The tunnel gateway applying for a routable IPv6 address B forthe device and setting up the mapping relation from the IPv6 address Ato the IPv6 address B.

Since the IPv6 address A may not be a routable IPv6 address in theInternet, at this time, the device could not start the remoteregistration mechanism directly. However, as the tunnel gateway throughwhich the device accesses the IPv6 network could route the messages thathave IPv6 addresses, the tunnel gateway could apply for, for the device,an IPv6 address which is routable in not only the IPv6 network which thedevice accesses but also the IPv6 network where the communicationcounterpart of the device locates, and the routable address is assumedto be the IPv6 address B. In the tunnel gateway, the IPv6 address B inthe source or destination address of the forwarding message is mapped tothe IPv6 address A. Then the device will have two IPv6 addresses, i.e.the IPv6 address A and the IPv6 address B. The IPv6 address A is used toforward the messages between the tunnel gateway and the device while theIPv6 address B is used to forward the messages between the tunnelgateway and the IPv6 network.

Step 411: The tunnel gateway registering at the home agent through theremote registration mechanism for the device and acquiring the homeaddress from the node registration agent.

After the device acquires the IPv6 address B, the tunnel gateway startsthe remote registration mechanism and registers the device to the homeagent, then informs the home agent of the IPv6 address B of the deviceas the forwarding address of the device. During this process, the tunnelgateway will also acquire the home address of the device and inform thedevice of the home address.

Step 412: The device acquiring the IPv6 address B from the tunnelgateway, taking the IPv6 address A as the forwarding address 1 and theIPv6 address B as the forwarding address 2.

The home address of the device is determined after the device acquiresit, and the IPv6 address A is taken as the forwarding address 1 of thedevice while the IPv6 address B is taken as the forwarding address 2 ofthe device. The device binds the IPv6 address A, the IPv6 address B andthe home address, and the messages sent to the device through theseaddresses could be used in a session in a mobile IPv6 terminal.

Steps 409 to 412 are the registration process at the tunnel gateway andthe home agent when the device accesses an IPv6 network through atunnel. Thereafter, communications between the device and thecommunication counterpart could be set up for providing the IPv6service.

Step 413: The communication counterpart sending the message to thedevice through the home address of the device.

When the device accesses the IPv6 network through a tunnel and completesthe registration at the tunnel gateway and the home agent, the messagesent to the device by the communication counterpart will be sent to thehome address of the device first.

Step 414: The home agent receiving and forwarding the message to theIPv6 address B.

The home agent forwards the message to the IPv6 address B of the deviceafter receiving the message sent from the communication counterpart sothat the tunnel gateway could receive the message.

Step 415: The tunnel gateway receiving and forwarding the message to theIPv6 address A.

The tunnel gateway forwards the message to the IPv6 address A of thedevice so that the device could receive the message sent by thecommunication counterpart through the tunnel.

Step 416: The device receiving the message, and starting a bindingupdate process.

The device starts a routine binding update process after receiving themessage and informs the communication counterpart about the IPv6 addressB, making the communication counterpart adopt the IPv6 address B of thedevice as the destination address when sending the subsequent messages.

Step 417: The communication counterpart communicating with the devicethrough the IPv6 address B of the device and providing the device withthe IPv6 service.

After the device informs the communication counterpart through thebinding update process of the IPv6 address B for use in communicatingwith the device, the subsequent messages sent by the communicationcounterpart will adopt the IPv6 address B of the device as thedestination address. The tunnel gateway receives the messages that havethe IPv6 address B from the communication counterpart, forwards themessages to the IPv6 address A, and eventually makes the messagesreceived by the device.

Steps 413 to 417 are the process of setting up communications betweenthe device and the communication counterpart for receiving IPv6 service.FIG. 5 is the schematic diagram illustrating how to provide a deviceaccessing the IPv6 network through a tunnel with the IPv6 service inaccordance with an embodiment of the invention.

After a device accesses the IPv6 network and completes the registration,if the device roams to an IPv4 network, the device then has to accessthe IPv6 network through a tunnel. Assuming that the IPv6 addressacquired when the device accesses the IPv6 network through a tunnel isthe IPv6 address C, since the IPv6 address C may not be a routable IPv6address, the device may not be able to communicate with thecommunication counterpart using the normal mobile IPv6 forwardingmechanism. At this time, the device needs to register to the tunnelgateway which will then assign a new IPv6 address for the device. ThisIPv6 address, assumed to be the IPv6 address D, will be routable in boththe IPv6 network which the device accesses and the IPv6 network wherethe communication counterpart of the device locates. The tunnel gatewayalso needs to register at the home agent for the device so as to informthe home agent of the forwarding address of the device, i.e. the IPv6address D. The gateway then sets up the mapping relation from the IPv6address C to the IPv6 address D.

After the device accesses the IPv6 network and registers to the homeagent, the device may roam to an IPv4 network and receive the IPv6service in the IPv4 network. FIG. 6 is a flow chart illustrating theprocess of providing the IPv6 service for a device roaming to an IPv4network in accordance with an embodiment of the invention. The processincludes:

Step 601: The device roaming to an IPv4 network;

Step 602: The device accessing the IPv6 network through a tunnel andacquiring the IPv6 address C;

Step 603: The device registering to the tunnel gateway;

Step 604: The tunnel gateway requesting for the device the IPv6 addressD which is routable in both the IPv6 network which the device accessesand the IPv6 network where the communication counterpart of the devicelocates, and setting up the mapping relation from the IPv6 address C tothe IPv6 address D;

Step 605: The tunnel gateway registering for the device to the homeagent and informing the home agent of the IPv6 address D as theforwarding address of the device;

Step 606: The device acquiring the IPv6 address D from the tunnelgateway, taking the IPv6 address C as the forwarding address 1 and theIPv6 address D as the forwarding address 2;

Step 607: The communication counterpart sending the message using thehome address of the device as the destination address;

Step 608: The home agent receiving the message, and then forwarding themessage to the IPv6 address D;

Step 609: The tunnel gateway receiving the message, and forwarding themessage to the IPv6 address C;

Step 610: The device receiving the message, and starting the bindingupdate process;

Step 611: The communication counterpart communicating with the devicethrough the IPv6 address D of the device to receive the IPv6 service.

The foregoing description is illustrative of the invention and not to beconstrued as limiting the invention. Various modifications, equivalentsubstitutions and improvement can be made without departing from thespirit and scope of the invention, and should be covered by the scope ofthe appended claims and their equivalents.

1. A method for providing Internet Protocol version 6 (IPv6) services,comprising: setting a node registration agent in advance in an IPv6network; a device accessing the IPv6 network and acquiring a forwardingaddress; registering the device to the node registration agent whichapplies for a home address for the device, registers the home address toa home agent and informs the device of the home address; a communicationcounterpart of the device sending a message using the home address asthe destination address; the home agent, after receiving the message,forwarding the message to the forwarding address of the device;providing the device with IPv6 services.
 2. The method according toclaim 1, wherein the step of the device accessing the IPv6 networkcomprises: the device accessing the IPv6 network from an InternetProtocol version 4 (IPv4) network through a tunnel gateway; the method,between the step of the device accessing the IPv6 network and acquiringthe forwarding address and the step of registering the device to thenode registration agent which applies for a home address for the device,registers the home address to a home agent and informs the device of thehome address, further comprises: registering the device to the tunnelgateway which applies for a routable IPv6 address for the device andsets up a mapping relation from the forwarding address to the routableIPv6 address; the step of registering the device to the noderegistration agent comprises: the tunnel gateway registering the deviceto the node registration agent; the step of the node registration agentinforming the device of the home address comprises: the noderegistration agent informing the tunnel gateway of the home address, andthe tunnel gateway informing the device of the home address; the step offorwarding the message to the forwarding address of the devicecomprises: the home agent forwarding the message to the routable IPv6address, the tunnel gateway forwarding the message to the forwardingaddress; and the method, between the step of the home agent forwardingthe message to the forwarding address of the device and the step ofproviding the device with IPv6 services, further comprises: the deviceinstructing the communication counterpart through a binding updateprocess to communicate with the device using the routable IPv6 address.3. The method according to claim 1 wherein the step of the deviceaccessing the IPv6 network comprises: the device directly accessing thelocal IPv6 network from an IPv6 network other than the local IPv6network; and the step of providing the device with the IPv6 servicescomprises: forwarding the message using the mobile IPv6 forwardingmechanism to provide the IPv6 services for the device.
 4. The methodaccording to claim 1, wherein the step of providing the device with theIPv6 services comprises: providing the device roaming to an IPv4 networkwith the IPv6 services, comprising: the device accessing the IPv6network through a tunnel and acquiring an IPv6 address 1; registeringthe device to the tunnel gateway; the tunnel gateway applying for aroutable IPv6 address 2 for the device and setting up a mapping relationfrom the IPv6 address 1 to the routable IPv6 address 2; the tunnelgateway registering the routable IPv6 address 2 to the home agent forthe device and informing the home agent that the routable IPv6 addressis the forwarding address of the device; the device acquiring the IPv6address 2 from the tunnel gateway; the communication counterpart of thedevice sending a message through the home address of the device; thehome agent receiving the message and forwarding the message to the IPv6address 2; the tunnel gateway receiving the message and forwarding themessage to the IPv6 address 1; the device receiving the message andstarting a binding update process; the communication counterpartcommunicating with the device through the IPv6 address 2, the devicereceiving the IPv6 services.
 5. A system for providing Internet Protocolversion 6 (IPv6) services, comprising: an IPv6 network; a home agent inthe IPv6 network; and a node registration agent used in the IPv6 networkto apply for a home address for a device from the home agent, registerfor the device to the home agent, and inform the device of the homeaddress.
 6. The system according to claim 5, further comprising: an IPv4network and a tunnel gateway; wherein the tunnel gateway locates betweenthe IPv4 network and the IPv6 network, supporting a remote registrationfrom the tunnel gateway to the node registration agent and forwardingdevice messages.
 7. The system according to claim 5, wherein the noderegistration agent is integrated on the home agent or is a separatedevice.
 8. The system according to claim 6, wherein the tunnel gatewayis a separate device or a device in the sub-network where the tunnelaccess device locates.
 9. The system according to claim 6, wherein thenode registration agent is integrated on the home agent or is a separatedevice.